The Sleep Heart Health Study (SHHS) was started in 1994 as a multicenter cohort study of the cardiovascular consequences of sleep-disordered breathing (SDB). The study's principal aims are to assess SDB as a risk factor for adverse cardiovascular outcomes, including incident coronary heart disease events, stroke, hyper-tension, and accelerated increase in blood pressure with age. The SHHS protocol added an assessment of SDB to ongoing cohort studies of cardiovascular and other diseases, including the Framingham Offspring and Omni cohorts, the Hagerstown and Minneapolis/St. Paul sites of the Atherosclerosis Risk in Communities (ARIC) Study, the Hagerstown, Sacramento, and Pittsburgh sites of the Cardiovascular Health Study (CHS), the Strong Heart Study (SHS) sites in South Dakota, Oklahoma, and Arizona, and cohort studies of respiratory disease in Tucson and of hypertension in New York. During its first four years (1994-1998), the SHHS was successfully started with full and high quality polysomnography (PSG) data obtained in the home from 6,440 participants, exceeding the recruitment target. The SHHS cohort, includes 3,039 men and 3,401 women 40 years of age or more, of whom 8.2 percent are African American, 9.6 percent are Native American, 1.3 percent are Asian, and 4.2 percent are Hispanic. In addition to PSG, data collection covered snoring and sleepiness and quality of life (QOL). Out-come assessment protocols are in place for all cohorts and the second SHHS examination is now in progress. Initial cross-sectional findings show that SDB is common and associated with hypertension and self-reported cardiovascular disease (CVD). This application requests five years additional support to continue the SHHS. Further follow-up is needed to have sufficient power to test the primary SHHS hypotheses. Additionally in Years 8-9, PSG will be repeated to further characterize SDB in the participants and to describe the natural history of SDB. During the first five years, the SHHS has shown that large-scale research on sleep, SDB, and disease risk can be conducted in the community. Follow-up of the SHHS cohort will provide the data needed to characterize the cardiovascular consequences of SDB, along with its natural history.